WhoBuilt

The Truth About The AI Bubble

Dec 22, 2025· 30 min· 104K views·Watch on YouTube

Speakers

Y Combinator hosts and guests Diana and Jared discuss AI models, startup opportunities, infrastructure investment, and hiring in The Light Cone’s 2025 year-in-review episode.

Model preferences are shifting

Diana says Anthropic became the most popular API among founders applying to YC’s Winter 2026 batch, edging out OpenAI. Gemini also rose to about 23%. The speakers point to coding performance, reasoning, and reliable web grounding as reasons founders and users choose different models.

Build products that can use the best model

The speakers describe relying on ChatGPT’s memory, Perplexity for research, and Gemini for grounded answers. Some startups are building orchestration layers to switch models or assign them different tasks. They say proprietary evaluations help companies identify which models work best for their own users and industries.

Infrastructure investment can create room for startups

Jared compares AI infrastructure spending to the telecom buildout that helped make YouTube possible. The speakers argue that overbuilding can leave abundant compute for application companies, even if infrastructure investors face losses. They describe the current period as a transition from heavy installation spending toward wider deployment of AI applications.

Specialized models and skills are spreading

The speakers see more founders building smaller models for particular devices, languages, and industries. They say reinforcement learning and fine-tuning can help specialized models outperform larger ones on domain tasks, citing a healthcare model with 8 billion parameters. They also caution that advances in frontier models can quickly erase a fine-tuning advantage.

AI companies still need people to grow

The hosts say early AI startups reached $1 million in ARR with very small teams, but that pattern had not yet carried through to $10 million in ARR without hiring. They suggest faster production raises customer expectations and keeps companies hiring to execute. Gamma is cited as reaching $100 million in ARR with 50 employees.

Takeaways

  • Track model quality for your own use case instead of committing to one provider.
  • Use evaluations to decide when to switch models or route tasks across them.
  • Build applications that can benefit from lower compute costs as infrastructure expands.
  • Specialized models can win on focused tasks, but keep measuring them against new frontier releases.
  • Treat AI efficiency as a way to meet rising customer expectations, not as a guarantee that hiring will stop.

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What was claimed 8

  • metric
    Anthropic: Number one API among YC Winter 2026 applicants; slightly ahead of OpenAI
    “the number one API is actually Anthropic”
    YouTube
    Unverified1 source· Talk
  • feature
    Claude: Models perform especially well on coding tasks
    “the models from Anthropic perform best at that”
    YouTube
    Unverified1 source· Talk
  • metric
    Gemini: About 23% of YC Winter 2026 applicants chose it
    “for Winter 2026, it's about 23%”
    YouTube
    Unverified1 source· Talk
  • feature
    Gemini: Grounding API uses Google's index to provide real-time information
    “Google's grounding API and its ability to use the Google index”
    YouTube
    Unverified1 source· Talk
  • uses
    “I switched to Gemini this year as my go-to model”
    YouTube
    Unverified1 source· Talk
  • invested in
    “I just funded a space fusion company that graduated called Zephyr Fusion”
    YouTube
    Unverified1 source· Talk
  • feature
    Reinforcement learning: Can help fine-tune open-source models for domain-specific tasks
    “create the best domain-specific, say, healthcare model, trained on a generic open-source model, just by fine-tuning it”
    YouTube
    Unverified1 source· Talk
  • metric
    Gamma: $100 million ARR with 50 employees
    “they got to $100 million in ARR with only 50 employees”
    YouTube
    Unverified1 source· Talk

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